Mid-infrared photoluminescence revealing internal quantum efficiency enhancement of type-I and type-II InAs core/shell nanowires: publisher's note

This publisher's note contains corrections to Opt. Lett.47, 5208 (2022)10.1364/OL.473154.

Mid-infrared photoluminescence revealing internal quantum efficiency enhancement of type-I and type-II InAs core/shell nanowires

Internal quantum efficiency (IQE) is an important figure of merit for photoelectric applications. While the InAs core/shell (c/s) nanowire (NW) is a promising solution for efficient quantum emission, the relationship between the IQE and shell coating remains unclear. This Letter reports mid-infrared PL measurements on InAs/InGaAs, InAs/AlSb, and InAs/GaSb c/s NWs, together with bare InAs NWs as a reference. Analyses show that the IQE is depressed by a shell coating at 9 K but gets improved by up to approximately 50% for the InGaAs shell coating at 40 -140 K and up to approximately 20% beyond 110 K for the AlSb shell. The effect is ascribed not only to the crystal quality but more importantly to the radial band alignment. The result indicates the high-temperature IQE improvement of the type-I and type-II c/s NWs and the appropriateness of the mid-infrared PL analyses for narrow-gap NW evaluation.

Stable Defects in Semiconductor Nanowires

Semiconductor nanowires are commonly described as being defect-free due to their ability to expel mobile defects with long-range strain fields. Here, we describe previously undiscovered topologically protected line defects with null Burgers vector that, unlike dislocations, are stable in nanoscale crystals. We analyze the defects present in semiconductor nanowires in regions of imperfect crystal growth, i.e., at the nanowire tip formed during consumption of the droplet in self-catalyzed vapor-liquid-solid growth and subsequent vapor-solid shell growth. We use a form of the Burgers circuit method that can be applied to multiply twinned material without difficulty. Our observations show that the nanowire microstructure is very different from bulk material, with line defects either (a) trapped by locks or other defects, (b) arranged as dipoles or groups with a zero total Burgers vector, or (c) have a zero Burgers vector. We find two new line defects with a null Burgers vector, formed from the combination of partial dislocations in twinned material. The most common defect is the three-monolayer high twin facet with a zero Burgers vector. Studies of individual nanowires using cathodoluminescence show that optical emission is quenched in defective regions, showing that they act as strong nonradiative recombination centers.

Si1-x Ge x /Si Interface Profiles Measured to Sub-Nanometer Precision Using uleSIMS Energy Sequencing

The utility of energy sequencing for extracting an accurate matrix level interface profile using ultra-low energy SIMS (uleSIMS) is reported. Normally incident O2 (+) over an energy range of 0.25-2.5 keV were used to probe the interface between Si0.73Ge0.27/Si, which was also studied using high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). All the SIMS profiles were linearized by taking the well understood matrix effects on ion yield and erosion rate into account. A method based on simultaneous fitting of the SIMS profiles measured at different energies is presented, which allows the intrinsic sample profile to be determined to sub-nanometer precision. Excellent agreement was found between the directly imaged HAADF-STEM interface and that derived from SIMS. Graphical Abstract ᅟ.

Endoultrasonography (EUS) examination of the esophagus in the diagnosis of esophageal duplication: a case report and a review of a literature

Esophageal duplication cysts are a rare medical entity. In most cases they are located at the level of the distal esophagus. Although our case is not unique, we want to focus on it as a reflection on diagnostic methods. The aim of this article is to show through the report on a case of esophageal duplication treated by us, followed by a review of similar cases in the literature, the utility of EUS in the diagnosis of upper-diaphragmatic and not communicating esophageal duplication. We report a case of a 43 year-old woman. She came to our attention for heartburn and retrosternal sense of space. The patient underwent an endoultrasonography (EUS) examination of the esophagus. The framework put EUS diagnosis of cystic formation of the esophagus (esophageal duplication cysts likely). We demonstrate that only EUS has a correlation with the determination of the pre-operative diagnosis with a statistical significance (p <0.001). In the diagnosis of esophageal not communicating duplication cysts EUS is the most specific diagnostic exam.

Realization of Vertically Aligned, Ultrahigh Aspect Ratio InAsSb Nanowires on Graphite

The monolithic integration of InAs(1-x)Sb(x) semiconductor nanowires on graphitic substrates holds enormous promise for cost-effective, high-performance, and flexible devices in optoelectronics and high-speed electronics. However, the growth of InAs(1-x)Sb(x) nanowires with high aspect ratio essential for device applications is extremely challenging due to Sb-induced suppression of axial growth and enhancement in radial growth. We report the realization of high quality, vertically aligned, nontapered and ultrahigh aspect ratio InAs(1-x)Sb(x) nanowires with Sb composition (xSb(%)) up to ∼12% grown by indium-droplet assisted molecular beam epitaxy on graphite substrate. Low temperature photoluminescence measurements show that the InAs(1-x)Sb(x) nanowires exhibit bright band-to-band related emission with a distinct redshift as a function of Sb composition providing further confirmation of successful Sb incorporation in as-grown nanowires. This study reveals that the graphite substrate is a more favorable platform for InAs(1-x)Sb(x) nanowires that could lead to hybrid heterostructures possessing potential device applications in optoelectronics.

Structural, optical and vibrational properties of self-assembled Pbn+1(Ti1-x Fex)nO(3n+1)-δ Ruddlesden-Popper superstructures

Bulk crystals and thin films of PbTi_1−xFe_xO_3−δ (PTFO) are multiferroic, exhibiting ferroelectricity and ferromagnetism at room temperature. Here we report that the Ruddlesden-Popper phase Pb_n+1(Ti_1−xFe_x)_nO_3n+1−δ forms spontaneously during pulsed laser deposition of PTFO on LaAlO₃ substrates. High-resolution transmission electron microscopy, x-ray diffraction and x-ray photoemission spectroscopy were utilised to perform a structural and compositional analysis, demonstrating that and . The complex dielectric function of the films was determined from far-infrared to ultraviolet energies using a combination of terahertz time-domain spectroscopy, Fourier transform spectroscopy, and spectroscopic ellipsometry. The simultaneous Raman and infrared activity of phonon modes and the observation of second harmonic generation establishes a non-centrosymmetric point group for Pb_n+1(Ti_0.5Fe_0.5)_nO_3n+1−δ, a prerequisite for (but not proof of) ferroelectricity. No evidence of macroscopic ferromagnetism was found in SQUID magnetometry. The ultrafast optical response exhibited coherent magnon oscillations compatible with local magnetic order, and additionally was used to study photocarrier cooling on picosecond timescales. An optical gap smaller than that of BiFeO₃ and long photocarrier lifetimes may make this system interesting as a ferroelectric photovoltaic.

The distinguishing cellular and molecular features of the endometriotic ovarian cyst: from pathophysiology to the potential endometrioma-mediated damage to the ovary

BACKGROUND

Clinical data suggest that the presence of an ovarian endometrioma may cause per se damage to the surrounding otherwise healthy ovarian tissue. However, the basic research has so far done a limited job in trying to understand the potential detrimental effect of an endometrioma presence in the context of the ovarian physiology. We have reviewed the literature with the aim of characterizing the pathophysiology of the endometrioma focusing mostly on factors and mechanisms potentially affecting the surrounding, otherwise normal, ovarian tissue.

METHODS

Comprehensive searches of PUBMED were conducted to identify human studies published from 1991 to 2013 in the English language on the cellular and molecular characterization of the various endometrioma components.

RESULTS

An endometrioma contains free iron, reactive oxygen species (ROS), proteolytic enzymes and inflammatory molecules in concentrations from tens to hundreds of times higher than those present in peripheral blood or in other types of benign cysts. The cyst fluid causes substantial changes in the endometriotic cells that it baths from gene expression modifications to genetic mutations The physical barrier between the cyst contents and the normal ovarian tissue is a thin wall composed of the ovarian cortex itself or fibroreactive tissue. ROS potentially permeating the surrounding tissues and proteolytic substances degrading the adjacent areas are likely to cause the substitution of normal ovarian cortical tissue with fibrous tissue in which the cortex-specific stroma is reduced. The fibrosis is associated with smooth muscle metaplasia and followed by follicular loss and intraovarian vascular injury. Follicular density in tissue surrounding the endometriotic cyst was consistently shown to be significantly lower than in healthy ovaries but this pathological change does not appear to be caused by the stretching of surrounding tissues owing to the presence of a cyst.

CONCLUSIONS

There is sufficient molecular, histological and morphological evidence, in part deriving from knowledge of the pathophysiology, to support a deleterious effect of the endometrioma on the adjacent ovarian cortical tissue, independent of the mere mechanical stretching owing to its size.

III-V quantum light source and cavity-QED on silicon

Non-classical light sources offer a myriad of possibilities in both fundamental science and commercial applications. Single photons are the most robust carriers of quantum information and can be exploited for linear optics quantum information processing. Scale-up requires miniaturisation of the waveguide circuit and multiple single photon sources. Silicon photonics, driven by the incentive of optical interconnects is a highly promising platform for the passive optical components, but integrated light sources are limited by silicon's indirect band-gap. III–V semiconductor quantum-dots, on the other hand, are proven quantum emitters. Here we demonstrate single-photon emission from quantum-dots coupled to photonic crystal nanocavities fabricated from III–V material grown directly on silicon substrates. The high quality of the III–V material and photonic structures is emphasized by observation of the strong-coupling regime. This work opens-up the advantages of silicon photonics to the integration and scale-up of solid-state quantum optical systems.

Structural analysis of strained quantum dots using nuclear magnetic resonance

Strained semiconductor nanostructures can be used to make single-photon sources, detectors and photovoltaic devices, and could potentially be used to create quantum logic devices. The development of such applications requires techniques capable of nanoscale structural analysis, but the microscopy methods typically used to analyse these materials are destructive. NMR techniques can provide non-invasive structural analysis, but have been restricted to strain-free semiconductor nanostructures because of the significant strain-induced quadrupole broadening of the NMR spectra. Here, we show that optically detected NMR spectroscopy can be used to analyse individual strained quantum dots. Our approach uses continuous-wave broadband radiofrequency excitation with a specially designed spectral pattern and can probe individual strained nanostructures containing only 1 × 10(5) quadrupole nuclear spins. With this technique, we are able to measure the strain distribution and chemical composition of quantum dots in the volume occupied by the single confined electron. The approach could also be used to address problems in quantum information processing such as the precise control of nuclear spins in the presence of strong quadrupole effects.

Population structure of the butternut canker fungus, Ophiognomonia clavigignenti-juglandacearum, in North American forests

The occurrence of multiple introduction events, or sudden emergence from a host jump, of forest pathogens may be an important factor in successful establishment in a novel environment or on a new host; however, few studies have focused on the introduction and emergence of fungal pathogens in forest ecosystems. While Ophiognomonia clavigignenti-juglandacearum (Oc-j), the butternut canker fungus, has caused range-wide mortality of butternut trees in North America since its first observation in 1967, the history of its emergence and spread across the United States and Canada remains unresolved. Using 17 single nucleotide polymorphic loci, we investigated the genetic population structure of 101 isolates of Oc-j from across North America. Clustering analysis revealed that the Oc-j population in North America is made up of three differentiated genetic clusters of isolates, and these genetic clusters were found to have a strong clonal structure. These results, in combination with the geographic distribution of the populations, suggest that Oc-j was introduced or has emerged in North America on more than one occasion, and these clonal lineages have since proliferated across much of the range of butternut. No evidence of genetic recombination was observed in the linkage analysis, and conservation of the distinct genetic clusters in regions where isolates from two or more genetic clusters are present, would indicate a very minimal or non-existent role of sexual recombination in populations of Oc-j in North America.

Actin cytoskeleton remodelling by sex steroids in neurones

Cell morphology and its interaction with the extracellular environment are integrated processes involving a number of intracellular controllers orchestrating cytoskeletal proteins and their interaction with the cell membrane and anchorage proteins. Sex steroids are effective regulators of cell morphology and tissue organisation, and recent evidence indicates that this is obtained through the regulation of the actin cytoskeleton. Intriguingly, many of these regulatory actions related to cell morphology are achieved through the rapid, nonclassical signalling of sex steroid receptors to kinase cascades, independently from nuclear alteration of gene expression or protein synthesis. The identification of the mechanistic basis for these rapid actions on cell cytoskeleton has special relevance for the characterisation of the effects of sex steroids under physiological conditions, such as for the development of neurone/neurone interconnections and dendritic spine density. This is considered to be critical for gender-specific differences in brain function and dysfunction. Recent advancements in the characterisation of the molecular basis of the extranuclear signalling of sex steroids help to clarify the role of oestrogen and progesterone in the brain, and may turn out to be of relevance for clinical purposes. This review highlights the regulatory effects of oestrogens and progesterone on actin cytoskeleton and neurone morphology, as well as recent progresses in the characterisation of these mechanisms, providing insights and working hypotheses on possible clinical applications for the modulation of these pathways in the central nervous system.

Blocking of indium incorporation by antimony in III-V-Sb nanostructures

The addition of antimony to III-V nanostructures is expected to give greater freedom in bandgap engineering for device applications. One of the main challenges to overcome is the effect of indium and antimony surface segregation. Using several very high resolution analysis techniques we clearly demonstrate blocking of indium incorporation by antimony. Furthermore, indium incorporation resumes when the antimony concentration drops below a critical level. This leads to major differences between nominal and actual structures.

Differential actions of estrogen and SERMs in regulation of the actin cytoskeleton of endometrial cells

Estrogen and selective estrogen receptor modulators (SERMs) differentially impact endometrial cell function, however, the biological basis of these differences is not established. Deregulated cell adhesion to the extracellular matrix, cell movement and invasion are related to endometrial disorders, such as endometriosis or endometrial cancer. Remodeling of the actin cytoskeleton is required to achieve cell adhesion and movement. Estrogen receptor (ER) regulates actin and cell membrane remodeling through extra-nuclear signaling cascades. In this article, we show that administration of 17beta-estradiol (E2) and tamoxifen (TAM) to immortalized Ishikawa endometrial cells or to human endometrial stromal cells (ESC) results in remodeling of actin fibers and cell membrane. This is linked to rapid phosphorylation on Thr(558) of the actin-binding protein moesin and enhanced migration and invasion of normal and Ishikawa cells. Raloxifene (RAL) does not result in moesin activation or actin remodeling. When endometrial cells are exposed to E2 in the presence of TAM or RAL, both SERMs interfere with the recruitment of moesin, with the remodeling of the cytoskeleton, and with cell movement and migration induced by E2. The differential actions of E2, TAM and RAL are linked to a distinct modulation of the extra-nuclear signaling of ER to G proteins and to the Rho-associated kinase. These findings increase our understanding of the actions of estrogen and SERMs in endometrial cells and highlight potential molecular targets to interfere with the estrogen-related altered cell adhesion encountered in endometrial disorders.

Drospirenone increases endothelial nitric oxide synthesis via a combined action on progesterone and mineralocorticoid receptors

BACKGROUND

Progestins have actions on the cardiovascular system, which depend on the structure as well as on receptor binding characteristics. Drospirenone (DRSP) is a progestin that uniquely interferes with the signaling of the mineralocorticoid receptor (MR). Hormone therapy containing DRSP results in blood pressure reduction in hypertensive post-menopausal women.

METHODS

We describe the effects of DRSP on endothelial nitric oxide (NO) synthesis and compare them with those of progesterone (P) and of medroxyprogesterone acetate (MPA). In addition, we herein tested the relevance of the anti-mineralocorticoid activity of DRSP for NO synthesis.

RESULTS

DRSP results in rapid activation of the endothelial NO synthase (eNOS) through mitogen-activated protein kinases and phosphatidylinositol 3-kinase as well as in enhanced eNOS expression. These actions depend on P receptor. When the cells are exposed to aldosterone, a reduction of eNOS expression is found that is antagonized by DRSP. This action is not shared by P or MPA. In addition, DRSP does not interfere with the induction or activation of eNOS induced by estradiol, as opposed to MPA.

CONCLUSIONS

DRSP acts on endothelial cells via a combined action through the P and MRs. These results help to interpret the anti-hypertensive effects of hormonal therapies containing DRSP.

[Indications and outcomes of surgical management of chronic pancreatitis: literature review]

Surgical management of chronic pancreatitis remains a challenge for surgeons. Last decades, the improvement of knowledge regarding to pathophysiology of chronic pancreatitis, improved results of major pancreatic resections, and new diagnostic techniques in clinical practice resulted in significant changes in the surgical approach of this condition. Intractable pain, suspicion of malignancy, and involvement of adjacent organs are the main indications for surgery, while the improvement of patient's quality of life is the main purpose of surgical treatment. The surgical approach to chronic pancreatitis should be individualized based on pancreatic anatomy, pain characteristics, exocrine and endocrine function, and medical co-morbidity. The surgical treatment approach usually involves pancreatic duct drainage procedures and resectional procedures including longitudinal pancreatojejunostomy, pancreatoduodenectomy, pylorus-preserving pancreatoduodenectomy, distal pancreatectomy, total pancreatectomy, duodenum-preserving pancreatic head resection (Beger's procedure), and local resection of the pancreatic head with longitudinal pancreatojejunostomy (Frey's procedure). Recently, non-pancreatic and endoscopic management of pain have also been described (splancnicectomy). Surgical procedures provide long-term pain relief, improve the patients? quality of life with preservation of endocrine and exocrine pancreatic function, and are associated with low mortality and morbidity rates. However, new studies are needed to determine which procedure is safe and effective for the surgical management of patients with chronic pancreatitis.

A novel icetexane diterpene, 5-epi-icetexone from Salvia gilliessi is active against Trypanosoma cruzi

In this work the effect of a novel compound, 5-epi-icetexone (ICTX) obtained from Salvia gilliessi Benth. (Labiatae), is studied on cultured epimastigotes of Trypanosoma cruzi (Tulahuen). It was found that the compound exerts an antiproliferative effect on the parasites at concentrations between 2.8 and 4.2 microM, and similar sensitivity in other strains (Dm28c, CL-Brener and Y-strain). The compound was deleterious at concentrations higher than 4.2 microM, with an estimated IC50 of 6.5+/-0.75 microM, but with low cytotoxicity to mammalian cells. These effects were irreversible, even at short times of exposure to the drug. In solution, ICTX showed to be stable for at least 96 h at 29 degrees C. With cytostatic dose a little percentage of parasites was resistant to the action of ICTX, and they continued growing although with different kinetic. By electron transmission microscopy, at dose of 4.2 microM an external vesiculization was observed on the first day of exposure to the compound, but the parasite cytoplasm became plenty of vacuoles and exhibited nuclear disorganization from the second day of exposure. It was concluded that ICTX is active against T. cruzi and may act by multiple mechanisms. In future, this novel icetexane diterpene may be a good candidate for therapeutic use against Chagas' disease.

An approach to the systematic distortion correction in aberration-corrected HAADF images

Systematic distortion has been analysed in high-angle annular dark-field (HAADF) images which may be caused by electrical interference. Strain mapping techniques have been applied to a strain-free GaAs substrate in order to provide a broad analysis of the influence of this distortion on the determination of local strain in the heterostructure. We have developed a methodology for estimating the systematic distortion, and we correct the original images by using an algorithm that removes this systematic distortion.

Expression of the ACC synthase and ACC oxidase coding genes after self-pollination and incongruous pollination of tobacco pistils

In tobacco, as in other species, ethylene is produced in response to pollination. Although tobacco is a self-compatible species, it displays unilateral incongruity with other Nicotiana plants. Incongruous pollination also results in ethylene production, but this production differs depending on the pollen used and is related to the extent to which pollen tubes grow in the tobacco style. In the investigation reported here we followed the expression of the ACC synthase- and ACC oxidase-coding genes upon pollination of tobacco pistils and compared self-pollination with incongruous pollination. The pattern of expression of these genes also correlated with pollen-tube growth, although wounding alone cannot explain the results obtained. We also examined the expression of these genes upon pollination of immature tobacco pistils, in which different pollen tubes grew indistinctly inside the tobacco style and reached the ovary at the same rate. In this situation no significant differences in gene expression could be observed between the different pollinations. Ethephon, a substance that produces ethylene, could, in some cases, minimize the arrest of incongruous pollen tubes inside the style.

Prevalence, donation practices, and risk assessment of blood donors with hemochromatosis

CONTEXT

Despite changes in eligibility policies, practical barriers limit blood donations from individuals with hemochromatosis. Increased knowledge of hemochromatosis donor characteristics may help foster further changes that will promote more donations.

OBJECTIVES

To estimate the prevalence of donors diagnosed as having hemochromatosis and to compare rates of unreported deferrable risks for transfusion-transmissible viral infections (TTVIs), positive screening test results for TTVIs, and donation patterns between hemochromatosis patient donors and donors reporting no medical conditions necessitating phlebotomy (non-health-related donors).

DESIGN

An anonymous mail survey conducted in 1998 as part of the ongoing Retrovirus Epidemiology Donor Study.

SETTING AND PARTICIPANTS

Among a stratified probability sample of 92 581 blood donors from 8 geographically diverse US blood centers, 52 650 (57%) responded.

MAIN OUTCOME MEASURES

Prevalence of hemochromatosis among blood donors; prevalence of unreported deferrable risks and positive screening test results for TTVIs among hemochromatosis patient donors vs non-health-related donors.

RESULTS

One hundred ninety-seven respondents (0.4%) identified themselves as hemochromatosis patients and 50 079 (95.1%) as non-health-related donors. An estimated 0.8% of all donations were from hemochromatosis patients, 45.8% of whom reported that they had donated blood to treat their illness. The proportion of repeat donors was higher in hemochromatosis patients than in non-health-related donors (83.5% vs 76.5%; P =.03). Among repeat donors, 68.7% of hemochromatosis patients reported donating at least 3 times in the past year compared with 49.1% of non-health-related donors (P<.001). The prevalence of unreported deferrable risks for TTVIs was similar in hemochromatosis patients (2.0%) and non-health-related donors(3.1%) as was the overall prevalence of positive screening test results (1.3% of hemochromatosis patients vs 1.6% of non-health-related donors).

CONCLUSIONS

Although significant numbers of hemochromatosis patients reported donating blood for therapeutic reasons, our findings suggest that this population does not present a greater risk to blood safety than other donors.

The potential impact of incentives on future blood donation behavior

BACKGROUND

It is important to assess the potential efficacy and safety of offering donation incentives as part of recruitment and retention programs.

STUDY DESIGN AND METHODS

In 1995, 7489 allogeneic donors responded to an anonymous mail survey that inquired about demographics, donation history, infectious disease risks, and the potential appeal of incentives.

RESULTS

The projected net effect of offering blood credits and medical testing would be to motivate, respectively, 58 percent and 46 percent of donors to return, whereas offering an item of limited value would motivate 20 percent to do so. First-time and younger donors reported more frequently than repeat or older donors that incentives would appeal to them. Donors attracted by cash were 60 percent more likely to have a risk for transfusion-transmissible infections (p = 0.03). Although not statistically significant, the odds of being an at-risk donor were higher among individuals attracted by tickets to events (OR 1.5) and extra time off work (OR 1.2).

CONCLUSION

These findings suggest that offering blood credits and (though to a lesser extent) items of limited value could be safe and effective strategies for retaining donors. Although medical tests were found to have broad appeal, studies are needed to identify tests in which donors would be most interested.

Responsiveness of dark-adaptation threshold to vitamin A and beta-carotene supplementation in pregnant and lactating women in Nepal

BACKGROUND

Impaired dark adaptation occurs commonly in vitamin A deficiency.

OBJECTIVE

We sought to examine the responsiveness of dark-adaptation threshold to vitamin A and beta-carotene supplementation in Nepali women.

DESIGN

The dark-adapted pupillary response was tested in 298 pregnant women aged 15-45 y in a placebo-controlled trial of vitamin A and beta-carotene; 131 of these women were also tested at 3 mo postpartum. Results were compared with those for 100 nonpregnant US women of similar age. The amount of light required for pupillary constriction was recorded after bleaching and dark adaptation.

RESULTS

Pregnant women receiving vitamin A had better dark-adaptation thresholds (-1.24 log cd/m(2)) than did those receiving placebo (-1.11 log cd/m(2); P: = 0. 03) or beta-carotene (-1.13 log cd/m(2); P: = 0.05) (t tests with Bonferroni correction). Dark-adaptation threshold was associated with serum retinol concentration in pregnant women receiving placebo (P: = 0.001) and in those receiving beta-carotene (P: = 0.003) but not in those receiving vitamin A. Among women receiving placebo, mean dark-adaptation thresholds were better during the first trimester (-1.23 log cd/m(2)) than during the second and third trimesters (-1.03 log cd/m(2); P: = 0.02, t test). The mean threshold of nonpregnant US women (-1.35 log cd/m(2)) was better than that of all 3 Nepali groups (P: < 0.001, t test, for all 3 groups).

CONCLUSIONS

During pregnancy, pupillary dark adaptation was strongly associated with serum retinol concentration and improved significantly in response to vitamin A supplementation. This noninvasive testing technique is a valid indicator of population vitamin A status in women of reproductive age.

Reduced mortality associated with body mass index (BMI) in African Americans relative to Caucasians

Although obesity is especially common in African-American women, the relationship between body mass index (BMI, kg/m2) and mortality primarily has been studied in Caucasians, and almost exclusively in average weight populations. In order to examine the relationship between race and mortality in a predominately overweight population, we assessed mortality in 6,602 parents of obese African-American and Caucasian subjects. Most parents of both races were overweight or obese: 87.8% of African-American mothers (mean BMI = 37.7) and 78.6% of Caucasian mothers (mean BMI = 34.9) had a BMI > or =27.3; 61.9% of African-American fathers (mean BMI = 31.5) and 63.6% of Caucasian fathers (mean BMI = 31.8) had a BMI > or =27.8. Even though African Americans had equivalent (fathers) or higher (mothers) average BMI and percentage overweight or obesity than Caucasians, unadjusted mortality rates were consistently lower in African Americans than in Caucasians. In a combined sample, income, age (linear, quadratic and cubic effects), gender, BMI (linear and quadratic), and race were significant predictors of mortality. Linear and quadratic effects of BMI were significant within race and in the combined sample, after controlling for the effects of all other predictor variables. Therefore, the mortality differences cannot be due to differences in age, income, BMI, or gender distributions. In addition, there was significant heterogeneity between races for all models examined, suggesting interactions between race and all other predictor variables. Moreover, there was a strong residual effect for race after accounting for the other variables. The highly selective and cross-sectional nature of this sample limits our ability to make specific BMI-associated risk estimates. However, the consistent differences between comparably ascertained racial groups sampled from the upper extreme of the BMI distribution provide support for a lower BMI-associated mortality rate in African Americans relative to Caucasians.

Fractionated ionizing radiation accelerates loss of amplified MDR1 genes harbored by extrachromosomal DNA in tumor cells

In tumor specimens such as those from neuroblastoma, ovarian, and lung carcinoma patients, the prevalence of extrachromosomal circular DNA molecules harboring amplified genes has been well established. In some cases, the amplified genes have been identified as oncogenes, and their increased expression appears to contribute to the maintenance and progression of the malignancy. The aim of this study was to investigate the effect of fractionated radiation treatment, given in daily doses similar to those administered clinically, on the stability of extrachromosomal circular DNA molecules in cancer cells. Our studies were conducted with multidrug-resistant KB cells, which harbor extrachromosomal copies of the multidrug resistance gene (MDR1) almost exclusively on circular DNA molecules of approximately 750 and 1500 kb pairs. This size range is representative of extrachromosomal circular DNA molecules that have been shown to harbor amplified oncogenes in vivo. Exponentially growing MDR KB cells were exposed to 1400 and 2800 cGy ionizing radiation administered in 7 and 14 fractions, respectively, at 200 cGy per fraction/day. A statistically significant decrease in MDR1 extrachromosomal gene copy number was reproducibly detected in the irradiated cells compared with unirradiated cells passaged for the duration of the experiment in the absence of radiation treatment. This decrease was accompanied by a reduction in multidrug resistance and in P-glycoprotein levels, as determined by clonogenic dose-response assays and Western analyses, respectively. P-glycoprotein is a multidrug transporter encoded by the MDR1 gene. Fluorescence in situ hybridization studies further determined that extrachromosomal circular DNA loss correlated to the entrapment of these DNA molecules in radiation-induced micronuclei. These results indicate that radiation-induced loss of extrachromosomally amplified genes from tumor cells via their entrapment in micronuclei contributes to the improved therapeutic response observed for some cancers.

Pupillary threshold as an index of population vitamin A status among children in India

Two hundred seven vitamin A-deficient southern Indian children aged 1-7 y (mean age: 56.9 mo) underwent testing of dark-adapted visual and pupillary thresholds in their village setting according to a previously reported protocol. One hundred thirty (62.8%) of the children also underwent serum retinol testing, and 178 (86.0%) participated in a randomized, placebo-controlled vitamin A dosing trial with pre- and postdose testing of dark-adaptation threshold. Most subjects (184 of 207, 88.9%) were able to complete pupillary testing, an objective sign requiring minimal cooperation, including a high proportion of the youngest children (72.2% of subjects aged 2 y). The proportion of children completing visual threshold testing, which requires greater understanding and cooperation, was significantly smaller than that able to complete pupillary testing (131 of 207, 63.3%; P < 0.0001, chi square). At baseline (predosing), the mean serum retinol concentration declined in linear fashion with a higher pupillary threshold (0.73 mumol/L with a score < or = 4; 0.47 mumol/L with a score > or = 8; P < 0.01). The mean pupillary threshold for these highly vitamin A-deficient Indian children (-0.622 log cd/m2) was significantly higher than that for 136 more moderately deficient Indonesian children (-0.985 log cd/m2; P < 0.001, two-sample t test) and 56 normal American children (-1.335 log cd/m2; P < 0.0001, two-sample t test). The improvement in pupillary dark-adaptation testing was not significant for children receiving vitamin A or placebo, though there was a nonsignificant trend toward greater improvement in children receiving vitamin A (P = 0.2, two-sample t test). Pupillary threshold testing represents a new, noninvasive, practical, and seemingly valid approach to assessing the vitamin A status of a moderately to severely deficient preschool population.

Comparison of saphenous vein graft relaxation between Plasma-Lyte solution and normal saline solution

Venospasm of saphenous vein grafts may damage endothelial cells and compromise early and late graft performance. Hence it is desirable to identify and use storage solutions that minimize vascular spasm during vein preparation. In view of this, we initiated isometric tension-recording studies in isolated canine and human saphenous vein to evaluate the acute, vasoactive effects of two storage solutions, Plasma-Lyte solution and normal saline solution. In initial experiments, canine saphenous veins were mounted in tissue baths containing physiologic salt solution and tonically constricted by 2 x 10(-6) mol/L norepinephrine. The physiologic salt solution in the bath was then replaced by Plasma-Lyte solution or normal saline solution containing the same norepinephrine concentration, and changes in contraction amplitude were recorded for 90 minutes. Storage in Plasma-Lyte solution at 37 degrees C completely relaxed norepinephrine-activated canine saphenous vein within 20 minutes, whereas veins remained partially constricted in normal saline solution. Both Plasma-Lyte solution and normal saline solution relaxed canine saphenous vein less at room temperature (25 degrees C) than at 37 degrees C, implying that warming of storage solutions in the operating room may promote graft dilation. To identify the mechanism by which Plasma-Lyte solution induced relaxation, we replaced its putative vasodilator components of gluconate and acetate with NaCl, but this alteration did not reduce relaxation induced by Plasma-Lyte solution. However, adding 1.6 mmol/L CaCl2 to Plasma-Lyte solution completely reversed the venodilation, suggesting that the low Ca2+ content of Plasma-Lyte solution confers its relaxant action. Finally, we tested the vasoactive effect of Plasma-Lyte solution on human saphenous vein obtained by discard from coronary bypass operations. Plasma-Lyte solution at 37 degrees C effectively dilated norepinephrine-activated human saphenous vein, inducing complete relaxation within 20 minutes. On this basis, we recommend the use of Plasma-Lyte solution as a venodilating storage solution during coronary bypass operations to optimize vein graft relaxation before implantation.

Subjective annoyance caused by environmental noise

We developed an acoustic study implemented throughout a neighborhood of Valencia (Spain). Acoustic recordings were made during the months of November and December 1989, on workdays between 9 a.m. and 1 p.m., and between 5 p.m. and 8 p.m. We also directly interviewed individuals living in this city area to determine their perception of noise and to evaluate the discomfort caused by it in daily life. A personal interview in the form of a questionnaire was employed to poll the neighborhood inhabitants on the magnitude of environmental noise and the distress it caused. The results showed that 40% of those interviewed considered environmental noise to cause considerable distress. On a 1 to 10 scale, over half of those interviewed rated noise in the neighborhood of 5 or higher. Traffic was considered the major source of noise, followed by noise from neighbors and factories. Of those interviewed, 9% changed the location of their bedroom as a result of noise, whereas 11% were forced to sleep with the windows closed for the same reason.

An improved spiral electrode applicator system for fetal heart rate monitoring

A new fetal scalp electrode applicator system uses a guide tube with increased curvature and a plunger mechanism to advance, rotate, and release the spiral electrode. Results of a preliminary survey among house staff who used the system in 51 patients indicated a favorable impression, with 96.1% of the applications rated as "much better," "better," or "same" as compared with the conventional system. The rate for a subset of 26 patients with limited cervical dilatation (1-3 cm) or high station of the presenting part (-1 to -3) was similarly good (92.3%). The characteristics found most favorable were the increased curvature for facilitating applications to high presenting parts, the plunger mechanism for applying the electrode, and better control of the guide tube.